In 540 beta-hemolytic streptococci, the rates of resistance to tetracycline, chloramphenicol, erythromycin, and clindamycin were 80.0, 22.8, 20.2, and 19.1%, respectively. Of the erythromycin-resistant isolates, 63.3% had the constitutive macrolide-lincosamide-streptogramin B (MLSB) resistance phenotype, 23.9% had the M phenotype, and 12.8% had the inducible MLSB resistance phenotype. The const...

In 540 beta-hemolytic streptococci, the rates of resistance to tetracycline, chloramphenicol, erythromycin, and clindamycin were 80.0, 22.8, 20.2, and 19.1%, respectively. Of the erythromycin-resistant isolates, 63.3% had the constitutive macrolide-lincosamide-streptogramin B (MLS(B)) resistance phenotype, 23.9% had the M phenotype, and 12.8% had the inducible MLS(B) resistance phenotype. The c...

Laboratory differentiation of erythromycin resistance phenotypes is poorly standardized for pneumococci. In this study, 85 clinical isolates of erythromycin-resistant (MIC > or = 1 microg/ml) Streptococcus pneumoniae were tested for the resistance phenotype by the erythromycin-clindamycin double-disk test (previously used to determine the macrolide resistance phenotype in Streptococcus pyogenes...

BACKGROUND Methicillin-resistant Staphylococcus aureus (MRSA) isolates are increasingly frequent causes of skin and soft-tissue infections or invasive infections in many communities. METHODS Prospective surveillance for community-acquired S. aureus infections at Texas Children's Hospital was initiated on 1 August 2001. Infections meeting the definition of community-acquired were identified. D...

Staphylococcus aureus remains a leading, virulent pathogen capable of expressing complex drug resistance that requires up to 2-4 days for laboratory analysis. In this study, we evaluate the ability of automated microscopy of immobilized live bacterial cells to differentiate susceptible from non-susceptible responses of S. aureus isolates (MRSA/MSSA, clindamycin resistance/susceptibility and VSS...

A clinical isolate of Streptococcus pyogenes UCN1 intermediate to erythromycin (MIC 1 mg/L) and susceptible to clindamycin (MIC 0.03 mg/L) harboured an inducible erm(TR) gene encoding a ribosomal methylase. We have selected in vitro, in the presence of concentrations of clindamycin ranging from 0.12 to 1 mg/L, one-step mutants that are highly resistant to this antibiotic (MIC 64 mg/L) at a freq...

BACKGROUND Staphylococcus aureus is the most commonly isolated organism from the different clinical samples in hospital. The emergence and dissemination of methicillin resistant Staphylococcus aureus (MRSA) and growing resistance to non-beta-lactam antibiotics is making treatment of infections due to this organism increasingly difficult. METHODS This study was conducted to determine the frequ...